Area Code 603-373 located in PORTSMOUTH, ROCKINGHAM, NH, more detail is as below. Place NPA (Numbering Plan Area) : 603 NXX (Local Number Prefix) : 373 City : PORTSMOUTH County : ROCKINGHAM State : NH (New Hampshire) NXX Use Type : Landline NXX Intro Version : 1999-07-22 FIPS (Federal Information Processing Standards) : 33015 LATA (Local Access Transport Area) : 122 Rate Center : PORTSMOUTH ZIP Code Count : 77 ZIP Code Frequency : 83 ZIP Code : 03801 Other Information NPANXX : 603373 County Population : 0 Switch CLLI (Common Language Location Identifier) : NASHNHO8DS0 MSA CBSA (Core Based Statistical Area) : Boston-Cambridge-Quincy, MA-NH MSA CBSA Code (Core Based Statistical Area) : 14460 Time Zone : Eastern (GMT -05:00) Observes Daylight Saving Time : Yes Company : CONVERSENT COMMUNICATIONS OF NEW HAMPSHIRE, LLC OCN (Operating Company Number) : 4053 Coverage Area Name : PORTSMOUTH Latitude : 43.0735 Longitude : -70.7636 ‹ previous : 603-373 next › : 603-374 Telephone Number List 603-373-0000 ~ 603-373-9999